ATLANTA – Among the emerging technologies and companies featured at last week's Georgia Life Sciences Summit was an innovative living implant for healing damaged knee cartilage – a concept pioneered by Genzyme (Cambridge, Massachusetts) with its cell therapy known as Carticel. But researchers from Georgia Institute of Technology (Georgia Tech; Atlanta) have added a nanotechnology enabled twist to the concept, producing what could be the next best solution for millions of aching knees.

"We came up with this idea because of the Carticel products from Genzyme," Yash Kolambkar, a PhD candidate at Georgia Tech and co-inventor of CartiMesh, told Medical Device Daily. "The problems associated with Carticel are that you don't know how long the solution of cells stays there. We use a nanofiber mesh – a thin membrane to cover the defect site and keep it in place to create a dual-layered construct."

Damage to knee cartilage — caused by injury, obesity or simply repetitive use over time (aka, getting older) — is permanent and leads to osteoarthritis, since that tissue has little capacity to regenerate. Until now, that is, with a little help from science.

CartiMesh consists of engineered tissue integrated with a biodegradable polymeric scaffold. To create the implant, articular cartilage cells are first isolated from either the patient's own cartilage or from a donor. Cells are then culture-expanded to the large numbers necessary for the implant. Then the cells are seeded on electrospun nanofiber meshes and cultured with certain biochemical cues for two weeks.

The meshes are scaffolds that mimic the extracellular matrix to which the cells in the body are accustomed. At the end of the culture period, the resulting CartiMesh is a dual-layered construct with a layer of cartilaginous tissue produced by the cells and a layer of nanofiber mesh with strong mechanical integration of the two layers.

"Even if we use donor cartilage cells, no specific processing is required because cartilage is immune-privileged tissue, eliminating rejection issues." Kolambkar said. "Nanofiber mesh has been around a long time. We just invented the dual construct."

Genzyme's Carticel uses a procedure known as autologous chondrocyte implantation (ACI) and was the first cell therapy to be approved by the FDA in the mid-1990s. It is used by orthopedic surgeons to treat patients who have clinically significant articular cartilage lesions on the thigh bone part of the knee caused by acute or repetitive trauma that have not responded to a prior cartilage repair procedure.

The surgeon provides Genzyme with a biopsy of healthy cartilage taken from a patient's knee in an arthroscopic procedure. Technicians at Genzyme's cell culture lab then grow millions of cells from the biopsy, and the cells then are delivered to the hospital, where the surgeon implants them into the patient's knee defect (MDD, March 27, 2008).

Studies had indicated good results for a term of up to seven years, but long-term data on Carticel is still in the works.

CartiMesh is seen as being a permanent solution.

CartiMesh, which was co-invented with Robert Guldberg, PhD, also a Georgia Tech professor, would be implanted so that the cartilaginous tissue fits into the defect and the nanofiber mesh is used to suture the implant in place. The strong mechanical integration between the two layers gives the construct mechanical stability in the harsh joint environment, which is essential for its survival, Kolambkar said.

Guldberg also is research director within the Georgia Tech/Emory Center for the Engineering of Living Tissues (GTEC), supported by the National Science Foundation (Arlington, Virginia) and the Georgia Research Alliance (Atlanta).

Within six to 12 months, it is expected that the cartilaginous tissue of CartiMesh would integrate with the surrounding host cartilage, the nanofiber mesh would safely degrade into the body and the cartilage joint surface would return to its normal structure and function.

The ultimate goal: elimination of joint pain and resumption of full mobility.

All of this is assumed, of course, because CartiMesh has yet to be tested in animals or people.

"We're focusing on licensing opportunities rather than going through trials on our own," said Ivan Mihailov, a law student at Emory University (Atlanta) who is working with Kolambkar to develop CartiMesh via GTEC. "We've developed bulletproof financials estimating that it would take $15 million to develop but would yield $50 million in revenues after it enters the market.

"We'll be hanging out afterwards, shamelessly handing business cards," Mihailov said at the Life Sciences Summit.

Kolambkar said his group was indeed approached by a few angel investors at the conference.